Tracer control for material working machines



Filed Oct. 18, 1935 June 1936- R BINGEL ET AL TRACER CONTROL FOR MATERIAL WORKING MACHINES 55 the intensity of the currents Patented June 30, 1936 PATENT OFFICE Tuscan. common For.

MATERIA WORKING MACHINE Rudolf Blngel, Berlin-Charlottenburg,

mut Wain ert, Berlin-Span and Hellda as- I signers to Siemens-Schuckertwerke Aktienge-' sellschaft, Berlin-Siemensstadt, Germany, a

corporation. of

Germany Application October 18, 1935, Serial No. 45,636

In Germany Go tober 2, 1934 3 Claims. 01. 90-62) Our invention relates to a tracer control for tool machines, and more particularly to material removing tool machines.

For manufacturing complicated work pieces 5 such as, for instance, dies, the well-known tracer controls are employed to advantage. The latter. are substantially based upon the idea that a tracer moves along a template or pattern, thereby controlling the feed motors of the tool in acthe resistance which opposes its movement. It is evident that such a tracer control will be only employed in such cases, in which the template or pattern coincides with the work to a sufiiciently high degree, i. e., the path of the tool must coincide with that of the tracer as accurately as possible. The tracer cannot, consequently, release control operations, it it has not at first been moved. The movements of the tracer then cause control impulses to be transmitted.' Even if these initial movements are relatively small they make themselves nevertheless conspicuous during the working operation, that is to say, the finished work difiers from the pattern by these initial control paths. Attempts must, consequently, be made in maintaining the initial control paths very small. To this end, it has already been proposed to arrange the control contacts not directly on the tracer, but to employ a mirror in connection with the tracer, which mirror reflects light upon movement of the mirrors is increased sufficiently by the optical method very small deflections of use of such a mirror device is,

ple and requires a careful attendance, insofar as a soiling of the mirror by dust or the like in the workshop may impair the accuracy of the control operation.

The object of my invention is "to provide a tracer control, whereby the above drawbacks are eliminated. This may be accomplished according to the invention by employing the hitherto known nozzle bolometer as an impulse transmitter for the control impulses. The nozzle bolometer as is well known is based upon the fact that two heated branches of a Wheatstone bridge connection are cooled by two currents of air equal in the position of rest, which currents issue from diameters and which are capable of being obstructed by a dia- The diaphragm is adjusted by an impulse transmitter. If the. diaphragm is brought out from its central position by rotation, then of air tor the two photocells. If the casing of the heated branches of the bridge connection varies, thus causing practically instantaneously a considerable change in resistance, which may be taken advantage of for the control current. The amplifying efiect oi the nozzle bolometer is so great 5 that a vacuum discharge tube for the control cir- (for instance for the magnetic clutches) may be readily controlled thereby. The mechanical contacts of the tracers hitherto employed are, consequently, replaced in the 10 arrangement according to the invention by the nozzle vane of the bolometer. The sensitiveness of this arrangement is so great that it probably represents the maximum t it will perhaps be necessary to provide a damping device for reducing the frequency of the control operations. Above all the combination of the nozzle bolometer with the vacuum discharge tube, whereby intermediate relays are eliminat- 20 ed, results in a construction of such working accuracy that the finished work practically does not differ from the pattern. The arrangement ac.- i

is so compact owing to the design of such bolometers that it may also 25 be readily employed for complicated cases. In the accompanying drawing an embodiment of my invention is illustrated in diagrammatic form. The tracer l is supported by a semispheric head 2 in the similarly shaped bottom of a tubu- 30 lar casing 3 in such a manner that the Ieeler end is may be moved in a spherical path. The rear end 4 of the tracer bar 20, which end is designed ln this case in the form of a ball loosely mounted in the end of the bar, engages a ball 35 socket 5 which forms one arm of a bell crank 6 pivotally moimted at E0. on a bracket 9. The position of bell crank G is biased by a spring 8 which is secured to the pin 9a provlded'onbracket 9. The force of the spring 8 causes rocking of the 40 ball socket 5 in such a manner that the socket maintains the tracer head 2 pressed against the semi-spherical bottom of the hood 3. An arm lll is connected to the other arm of hell crank 6 and carries the nozzle vane ll 01 the 45 bolometer. l2 and I3 denote the airoutlet ports of the bolometer which are controlled by the bell vane II and I4 the diaphragm blower. 22 and 23 represent the heatedbolometer wires, the temperatures or which so are controlled by vane II, which is assumed to move between the wires and their operating nozzles l2, B respectively as is wellknown in the art. The stops l5 and IS limit the deflection oi the vane within a given range. For adjusting the hat may be obtained. In some cases 15 nozzle vane I! with respect to the air outlet ports l2 and I3 the arm 50 is not firmly secured to bell crank 6, but by as shown, which consists of a bolometer and a tracer control, is, for instance, arranged on the tool support 20.

The tracer control may be improved according to the invention by rendering the bolometer arrangement electrically so sluggish that mechanical oscillations of the order of magnitude of those generally occurring in workshops and the like are rendered ineffective. This thermal sluggishness may be attained, for instance, by correspondingly increasing the thickness or the vane controlled bridge wires 22, 23, to impart to them greater heat inertia, which prevents an appreciable cooling by accidental vibrations of the vane.

control of tool machines, above all for material alone produced by the tool ma-,

chine itself, but-also by machines located nearof the nozzle bolometer might be used. This method, however, is employed according to the invention, but the movement of the nozzle vane is damped only to a very slight extent and the elim= ination of the efl'ect'of the undesired vibrations.

occurs instead in the electrical portion of the con trol by making the controlled resistances so slugish that the detrimental oscillations of undesired frequency are rendered ineiIective; The extent to which the frequency must be damped depends uponthe circumstances, under which the machine is to be operated. In many cases it will 'be suflicient ii. the oscillations above 5 or periods are damped,

We claim as our invention: 1. In a tracer control device for tool machines or the like, the combination 0! a tracer bar dis- It the instrument is employed for the 7 posed to follow a given templet, with a nozzle bolometer relay for controlling the tool movement tively connected with said tracer bar to partake in the movements of the latter for controlling the bolometer wiretemperatures in accordance with said tracer movements.

In a tracer control device for tool machines or the like, the combination of a tracer bar having a semi-spherical bearing head, a similarly move on a spherical path, a pivoted bell crank having the rear end of the tracer bar socketed in one or its arms so that the bell crank is rocked when the tracer bar is operated by the given templet, a nozzle bolometer relay for controlling the tool movement 01 the tool machine, said bolometer having air nozzles and electrically conducting wires, disposed in be heated by electric to move between sai-d nozzles and said wires and being attached to 'the other arm of said bell crank, to control the temperature 01' said wires in accordance with the movements of said tracer bar.

3. In a tracer control device for tool machines or the like, the combination of a tracer bar having a semi-spherical bearing head, a similarly contoured se'cket for said head to permit the tracer feeler end to move on a spherical patina pivoted bell crank having the rear end of the tracer bar socketed in one of its arms so that the bell erank is rocked when the tracer bar is eperated by the given 'templet, a nozzle bolometer relay for controlling r being attached to the other arm of said bell crank, to control the temperature of said wires in accordance with the movements 01' said wires having a sufllcient thickness to impart essential temperature ehanges in the wires. RUDOLI' BINGEL.

HEILMUT WEINERT. 

